how did the prediction turn out to wrong? like, that quote seems to imply that there was insufficient agriculture to sustain the current generation of humans, n

how did the prediction turn out to wrong? like, that quote seems to imply that there was insufficient agriculture to sustain the current generation of humans, not just the next (since sufficiently brutal "crash programs" could keep the population from growing entirely.) and it's not like there was any big leap in ag sci enabling expansion, like the Haber process. like, I'm literally just confused, did he forget to carry the 2 or something?